Our long term objective is to understand the mechanisms and role of fungal adhesions in cellular interactions. Candida albicans infections remain a significant cause of morbidity and mortality, and are often inadequately controlled with the available antifungals, thus creating a serious health concern. We propose the following specific aims: 1. Test the idea that Candida albicans adhesin AIs5p undergoes a conformational shift from a non-aggregative to aggregative state following adherence to substrate. Conformational shifts will be monitored by CD spectroscopy. 2. Test the idea that AIs5p mediated aggregation features amyloid characteristics. CD spectroscopy, the binding of amyloid specific dyes, and electron microscopy will be tested on soluble AIs5p fragments and aggregates 3. Test the idea that the tandem repeat region of AIs5p mediates homotypic binding facilitating aggregation. Non-denaturing gel electrophoresis on soluble protein fragments and binding assays with a cell-surface expressed AIs5p variant will be performed. 4. Test the idea that the N-Terminal globular Ig-like domain of AIs5p mediates adhesion to substate. Binding assays with purified AIs5p Ig -like protein fragments will be performed. These experiments will help explain the behavior of a large group of proteins from other pathogens.